(1) Field of the Invention
This invention generally relates to a method and apparatus for firing a fully automatic gun underwater using a special blank round.
(2) Description of the Prior Art
Underwater guns firing fully automatically have come under consideration in naval applications recently for swimmer operations, mine clearance, anti torpedo close-in defense, and other uses. These proposed uses have been supported by the development of extremely low drag superactivating projectiles, which allow ranges and velocities comparable to conventional guns fired in air. Design of the weapon remains a problem, particularly if it is intended to fire fully automatically (i.e., like a machine-gun). Propellants designed to accelerate a projectile down a barrel can generate catastrophic pressure levels if the barrel is full of water at firing. Consequently, some means must be devised to keep the barrel clear of water during the firing of live rounds. Proposals to date have involved complex mechanical systems adding weight and expense to the gun system. The present invention does not alter the mechanical operation of the gun, adds no parts, and relies on the blank round to clear the barrel.
Known methods and apparatuses for firing an automatic weapon underwater so as to obtain a "dry barrel" firing are limited to the capping of a gun's barrel and include the following:
U.S. Pat. No. 1,271,640 to Wentling discloses an underwater weapon which prevents water from entering the barrel by the use of valve 21 at the end of the barrel. A fired bullet opens the valve as it exits the barrel. A mechanism is provided to shut the valve after the bullet exits the valve but before the water enters the barrel.
U.S. Pat. No. 3,300,888 to Belcher et al. discloses an underwater gun which is sealed with a plastic cap 46 at the end of its barrel. The gun fires when it is struck against an object in a spearing motion. When the end of the barrel strikes an object, the telescoping barrel collapses and the firing pin strikes the cartridge thus firing the bullet. The bullet flies through the dry barrel and blows the cap 46 off. A new cap must be affixed and another cartridge must be loaded after every shot and this must be done out of the water.
U.S. Pat. No. 3,453,763 to Barr et al. discloses an underwater pistol capable of holding several cartridges. Each cartridge forms its own dry disposable barrel that is elongated and sealed at both ends. The pistol can be reloaded underwater and can fire multiple shots.
U.S. Pat. No. 3,476,048 to Barr et al. disclose cartridges for use with the gun disclosed in Barr et al. U.S. Pat. No. '763. The cartridges each form their own dry disposable barrels and are elongated and sealed at both ends.
U.S. Pat. No. 3,494,060 to Hendricks discloses an underwater gun having a plug 121 that is broken when the round is fired. The gun must be reloaded out of the water and capped with a new plug before being fired again.
U.S. Pat. No. 4,077,147 to Donnard et al. discloses an underwater pistol which uses an expendable cartridge-barrel. The one-shot, sealed cartridge-barrel is loaded into the gun and fired. Upon firing, a seal 51 at the end of the barrel is broken. The weapon can be reloaded underwater.
U.S. Pat. No. 4,266,358 to Phillips et al. discloses an underwater firearm having a large magazine for holding multiple shots that are spring loaded in the firing chamber.
U.S. Pat. No. 4,357,888 to Phillips et al. discloses special ammunition for use with the firearm of Phillips et al. U.S. Pat. No. '358. The projectiles are self-propelled such that upon firing, the propellant in the projectile is ignited and continues to provide propulsion after the projectile exits the firearm.
The above devices are substantially unacceptable for solving the problem of repeated underwater firing of a conventional weapon without the use of special caps and/or valves therein.